<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    div{
      /*important重要的*/
      background-color: green !important;
    }
    #d1{
      color: red;
      background-color: blue;
    }
  </style>
</head>
<body>
  <div id="d1">
    <p>这是p标签</p>
    <span>这是span</span>
    <a href="">这是超链接</a>
  </div>
</body>
</html>